Operation checking method for adaptive front lighting system

ABSTRACT

An operation checking method for an adaptive front lighting system (AFS), which is applicable to on-line automobile inspections involves an operation checking program prepared to activate the AFS in a manner to perform its prescribed headlamp illumination redirecting function and stored in advance in an in-vehicle ECU. While a finished vehicle remains stationary at an inspection zone of an automobile production and assembly line, the operation checking program is executed. During a run-time of the program, an inspection is performed to determine whether the headlamp illumination has been redirected by the AFS in leftward, rightward, downward and upward directions in a predetermined sequence as specified by the operation checking program.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is the US National Phase of InternationalApplication PCT/JP2004/019139, filed 15 Dec. 2004, which claims priorityunder 35 USC 119 based on Japanese patent application No. 2003-418640,filed 16 Dec. 2003. The entire contents of the International andpriority Japanese applications are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a method of checking operation of anadaptive front lighting system that is able to adjust the direction ofheadlamp illumination in accordance with both steering angle and vehiclespeed.

BACKGROUND ART

Advanced technologies to adjust the direction of headlamp illuminationin accordance with steering angle and vehicle speed, generally called“adaptive front lighting system (AFS)”, have been developed and put intopractical use in recent years. One example of such technologies isdisclosed in Japanese Patent Laid-Open Publication (JP-A) No. 01-111546.

As shown in FIG. 6 hereof, the disclosed technology varies the length,width and direction of the headlamp illumination according to the angleof the steering wheel and the vehicle speed. Reference numeral 2 denotesa headlamp illumination pattern provided when the steering wheel isturned to the left. Similarly, when the steering wheel is turned to theright, a headlamp illumination pattern denoted by 4 is obtained. Theheadlamp illumination pattern can thus be redirected depending on thesteering angle. A long slim headlamp illumination pattern denoted by 5is provided when the vehicle is traveling straight ahead at high speeds,while a relatively wide but shorter headlamp illumination patterndenoted by 3 is provided when the vehicle is traveling straight ahead atlow speeds. Headlamps of the vehicle are denoted by reference numeral 6.

Operation of the adaptive front lighting system is checked or inspectedby the automobile manufacturer before shipment of the vehicle. For suchinspection, the automobile manufacturer must prepare a test course orcircuit sufficiently large enough to permit actual traveling of thevehicles. When darkness arrives or during nighttime, finished vehiclesare put into actual run or traveling on the circuit so as to determinewhether the adaptive front lightening system operates in a specifiedmanner depending on steering angle and vehicle speed. Obviously, thosevehicles produced during daytime must stand by in an appropriate space,such as a parking lot, before the inspection during darkness is started.

The conventional operation checking method discussed above requires alarge amount of facility cost due to the necessity of the relativelylarge test circuit and parking lot.

Furthermore, due to a large time lag existing between the production andthe checking of the vehicles equipped with the adaptive front lightingsystem, even if a fault is detected by the checking process, informationabout the detected fault is fed back with a great delay to a relevantpart of an automobile production and assembly line. This allowsproduction of a large number of vehicles with defective adaptive frontlighting systems installed therein.

It is, therefore, an object of the present invention to provide a methodof checking operation of an adaptive front lighting system, which can beapplied to on-line inspections of an automobile production and assemblyline.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a method ofchecking operation of an adaptive front lighting system having afunction of redirecting headlamp illumination in both a horizontaldirection and a vertical direction in accordance with steering angle,traveling speed and incline of a vehicle, the method comprising thesteps of: storing an operation checking program in advance in anelectronic control unit installed in the vehicle, the program beingprepared to activate the adapted front lighting system to perform thefunction thereof under the control of the electronic control unit suchthat the headlamp illumination is redirected leftward, rightward,downward and upward in a predetermined sequence; while the vehicleremains stationary at an inspection zone of an automobile production andassembly line, energizing the electronic control unit with electricpower supplied from a battery installed in the vehicle and switching onheadlamps of the vehicle; then, causing the operation checking programto run, thereby activating the adaptive front lighting system; andduring a run-time of the operation checking program, performing aninspection to determine whether the headlamp illumination has beenredirected leftward, rightward, downward and upward in the predeterminedsequence specified in accordance with the operation checking program.

By virtue of the operation checking program stored in advance in theelectronic control unit, the operation checking method of the presentinvention can be applied to an on-line automobile inspection systemwherein necessary inspection and checking processes are carried outwhile the vehicle remains stationary at the inspection zone of theautomobile production and assembly line. Accordingly, it is no longernecessary for the automobile manufacturer to make a huge investment inthe construction of AFS inspection facilities including new test courseand parking lot.

Preferably, the operation checking program can be executed only onetime. This arrangement will preclude the change of accidental activationof the adaptive front lighting system which may otherwise occur duringtraveling of the vehicle when the operation checking program can beexecuted more than one time.

During the run-time of the operation checking program, the electroniccontrol unit may perform a diagnostic operation to detect the occurrenceof a fault on the basis of answer back signals from structuralcomponents of the adaptive front lighting system, and when a faultoccurs, the electric control unit issues a signal to turn on a warninglamp on a dashboard of the vehicle.

Information about the detected fault is fed back to a relevantprocessing zone of the automobile production and assembly line to takeappropriate measures on a real-time basis.

In one form of the invention, the inspection performed during therun-time of the operation checking program comprises a visual inspectionby a human operator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C are schematic plan views showing the operation of anadaptive front lighting system incorporated in a motor vehicle;

FIGS. 2A, 2B and 2C are schematic side views illustrative of theoperation of an automatic leveling system associated with the adaptivefront lighting system of the motor vehicle;

FIG. 3 is a block diagram showing the general configuration of anoperation checking system for checking operation of the adaptive frontlighting system according to an embodiment of the present invention;

FIG. 4 is a flowchart showing a sequence of operations achieved inaccordance with an operation checking program so as to check operationof the adaptive front lighting system;

FIG. 5 is a flowchart showing a sequence of operations achieved to carryout an operation checking method of the invention on a vehicleproduction and assembly line; and

FIG. 6 is a schematic plan view showing headlamp illumination patternsachieved by a conventional adaptive front lighting system.

DETAILED DESCRIPTION OF THE INVENTION

One preferred embodiment of the present invention will be describedbelow in greater detail with reference to the accompanying sheets ofdrawings.

FIGS. 1A, 1B and 1C schematically show operation of an adaptive frontlighting system (AFS) incorporated in a motor vehicle 10. The AFSincludes left and right headlamps 11 and 12 and an in-vehicle electroniccontrol unit (ECU) 15. The ECU is configured to adjust the directions ofillumination of the respective headlamps 11, 12 on the basis of vehiclespeed information and steering angle information. The steering angleinformation is supplied from a steering angle sensor 14, which isprovided to detect steering angle of a steering wheel 13. The vehiclespeed information is supplied from a vehicle speed sensor (not shown).

When the steering wheel 13 is turned to the left as shown in FIG. 1B,the AFS, under the control of the in-vehicle ECU 15, changes thedirections of illumination of the headlamps 11, 12 leftward from thenormal straight-ahead direction. In this instance, if the vehicle speedinformation indicates that the current vehicle speed is below apredetermined speed (20 km/h, for example), the in-vehicle ECU disablesthe AFS and, hence, the redirection or bending of headlamp illuminationdoes not occur.

Similarly, when the steering wheel 13 is turned to the right as shown inFIG. 1C, the in-vehicle ECU 15 controls the AFS such that the directionsof illumination of the headlamps 11, 12 are changed to the right. Inthis instance, if the vehicle speed is below the predetermined speed,the redirection of headlamp illumination does not take place.

FIGS. 2A, 2B and 2C schematically illustrate operation of an automaticleveling system incorporated in the adaptive front lighting system.

In a normal headlamp illuminating condition shown in FIG. 2A, beam axesof the headlamps 11, 12 are set to be slightly inclined downward (at anangle θ of about 2°, for example) from the horizontal.

When a heavy load 103 is placed in a rear trunk room of the vehicle 10,the rear of the vehicle 10 sinks down, causing the headlamp beam axes totilt upward and become lying above the horizontal, as denoted by numeral104 shown in FIG. 2B.

To avoid this problem, the automatic leveling system includes a frontlevel sensor 16 and a rear level sensor 17 that are used in combinationto detect an incline of the vehicle 10, as shown in FIG. 2C. On thebasis of the detected vehicle incline, the in-vehicle ECU 15 activatesleft and right auto-leveling mechanisms to bend the beam axes of theheadlamps 11, 12 downward until the beam axes assume the normal positionshown in FIG. 2A.

Now, description will be given to an operation checking system, which isemployed in accordance with the present invention to check operation ofthe adaptive front lighting system of the type described above.

FIG. 3 shows in block diagram a general configuration of the operationchecking system and the adaptive front lighting system linked with eachother. The adaptive front lighting system includes a left horizontalswiveling mechanism 18 for changing the direction of illumination(including illumination pattern) of the left headlamp 11 in a horizontalplane, a left auto-leveling mechanism 19 for adjusting the level orvertical position of a beam axis of the left headlamp 11, a righthorizontal swiveling mechanism 21 for changing the direction ofillumination of the right headlamp 12 in a horizontal plane, and a rightauto-leveling mechanism 22 for adjusting the vertical position of a beamaxis of the right headlamp 12. The adaptive front lighting systemfurther includes an in-vehicle electric control unit (ECU) 15 soconfigured as to control operations of the swiveling and auto-levelingmechanisms 18, 19, 21 and 22, an in-vehicle battery 23 for supplyingelectric power to the ECU 15, and a switch means 24 including variousoperation switches such as a main switch (ignition key switch) and acombination switch. Though not shown, the left and right horizontalswiveling mechanisms 18 and 21 each have a swivel actuator such asstepping motor. Similarly, the left and right auto-leveling mechanisms19 and 22 each have a leveling actuator such as stepping motor. Thein-vehicle ECU 15 is also connected to the steering angle sensor 14(FIG. 1), the non-illustrated vehicle speed sensor, and the front andrear level sensors 16, 17, so that detection signals from the respectivesensors are inputted to the ECU 15.

The operation checking system generally comprises an operation checkingprogram storage part or section 25 always remaining in a memory of thein-vehicle ECU 15 and storing therein an operation checking program(described later) to be achieved by a microprocessor of the in-vehicleECU 15, and a run instruction means 26 for supplying a program runinstruction signal to the in-vehicle ECU 15 to thereby execute theoperation checking program. The run instruction means 26 may besubstituted by an on-off operation of one of the existing switches 24,such as a passing switch, that is repeated in several times during aprescribed short duration of time.

FIG. 4 is a flowchart showing a sequence of operations achieved by themicroprocessor of the ECU 15 in accordance with the operation checkingprogram so as to check the operation of the adaptive front lightingsystem.

A step ST01 determines whether or not a program run instruction signalfrom the run instruction means 26 (FIG. 3) has been received. If theresult of determination is affirmative, the control procedure goes on toa step ST02. Alternatively, if the determination result is negative, thecontrol procedure is terminated.

The step ST02 determines whether or not the operation checking programhas been executed before. If the result of determination is affirmative(i.e., log or record indicates prior execution of the operation checkingprogram), the control procedure is terminated. Alternatively, if thedetermination result is negative, the control procedure goes on to astep ST03.

At the step ST03, the headlamp illumination direction is bent or changedto the left. More specifically, the left and right horizontal swivelingmechanisms 18 and 21 (FIG. 3) operate to direct illumination patterns ofthe left and right headlamps 11, 12 in a leftward direction.

The step ST03 is followed by a step ST04 where the headlamp illuminationdirection is bent or changed to the right. Stated more specifically, theleft and right horizontal swiveling mechanisms 18, 21 operate toredirect illumination patterns of the left and right headlamps 11, 12 ina rightward direction.

After the step ST04, the control procedure advances to a step ST05 whereillumination patterns of the left and right headlamps 11, 12 arereturned to a normal straight-ahead position.

The step ST05 is followed by a step ST06 where the left and rightauto-leveling mechanisms 19 and 22 (FIG. 3) are operated to dip orincline respective beam axes of the left and right headlamps 11, 12 in adownward direction.

Subsequently, a final step ST07 operates the left and rightauto-leveling mechanisms 19, 22 so that the beam axes of the left andright headlamps 11, 12 return to their original positions.

As understood from the foregoing description, the operation checkingprogram is prepared to activate the adaptive front lighting system in amanner to perform the function thereof under the control of thein-vehicle ECU 15 such that the headlamp illumination is redirectedleftward, rightward, downward and upward in a predetermined sequence.

The operation checking program does not require on-site installation.Namely, it is not necessary for an inspection operator to install theoperation checking program when a finished vehicle is transferred to aninspection site or zone provided at a downstream end of an automobileproduction and assembly line. Rather, the operation checking program ispreferably installed in advance in the storage section 25 (FIG. 3) ofthe ECU 15 at the same time other control programs are installed in thememory of the ECU 15 before the ECU 15 is assembled in the vehicle. Thesteps ST03-ST07 shown in FIG. 4 may be achieved in a different sequencethan as discussed above.

FIG. 5 is a flowchart showing a sequence of operations achieved to carryout the operation checking method of the invention with respect tofinished motor vehicles equipped with the adaptive front lightingsystem.

At a first step ST11, a finished motor vehicle equipped with an adaptivefront lighting system (AFS) is transferred into a finished vehicleinspection site or zone that is provided at a downstream end of anautomobile production and assembly line.

Then, at a step ST12, a main switch (ignition key switch) forming a partof the switch means 24 (FIG. 3) of the vehicle is turned on whereuponthe in-vehicle ECU 15 is energized with electric power supplied from thein-vehicle battery 23. At the same step ST12, a headlamp switch isturned on to place the left and right headlamps 11, 12 in a turn-onstate.

Subsequently, at a step ST13, an inspection operator provides a programrun instruction through the run instruction means 26 (FIG. 3) to thein-vehicle ECU 15 whereupon the operation checking program stored in theoperation checking program storage section 25 of the in-vehicle ECU 15is caused to run. The program run instruction signal may be supplied ina different manner than as achieved by the inspection operator.

At a next following step ST14, the inspection operator undertakes avisual inspection to determine whether the illumination patterns of theleft and right headlamps have been redirected leftward and rightward andalso inclined downward in the predetermined sequence as specified by theoperation checking program. The visual inspection may be replaced withan automated inspection using a suitable electronic optical instrumentsuch as an illumination sensor.

While the AFS performs its prescribed swiveling and auto-levelingoperations in accordance with the operation checking program (i.e.,during a run-time of the operation checking program), the in-vehicle ECU15 performs a diagnostic operation by continuously monitoring answerback signals from structural components of the AFS including theautomatic leveling system (i.e., the left and right swiveling mechanisms18, 21 including respective actuators, the left and right auto-levelingmechanisms 19, 22 including respective actuators, the steering anglesensor 14, the un-shown vehicle speed sensor, and the level sensors 16,17). Through the diagnostic operation, the ECU 15 detects, on the basisof the answer back signals, a fault which may occur to one of theactuators, sensors and wire harnesses in the form of a malfunction ofcomponent, faulty wiring, or breaking of wire. When a fault occurs, theECU 15 issues an electric signal to turn on a warning lamp (not shown)on the dashboard of the vehicle. Thus, the inspection operator canreadily acknowledge the occurrence of a problem.

Subsequently, a pass-fail judgment is made at a step ST15. In thisinstance, information obtained through visual inspection by theinspection operator and information given by the warning lamp are usedin combination to determine whether operation of the AFS incorporated inthe vehicle is acceptable. If the judgment is affirmative, the proceduregoes on to a step ST16 where the vehicle with acceptable AFS istransferred to a next subsequent processing zone or station.

Alternatively, if the judgment at the step ST15 is negative, theprocedure is blanched to a step ST 17 where the vehicle with defectiveAFS is removed from the vehicle production and assembly line foroff-line repairing of the defective AFS. Then, at a step ST18,information concerning a fault or failure obtained during inspectionwith respect to the defective AFS is fed back to a relevant processingpart or station of the vehicle production and assembly line for takingappropriate measures to remove the fault on a real-time basis. The stepST18 is particularly advantageous because if a fault detected by thestep ST14 with respect to one AFS is due to faulty wiring, it willprovably occur that all of the succeeding AFSs also have the same faultas they are produced in the same lot as the detected faulty AFS.

It will be readily appreciated that the operation checking method of thepresent invention can be carried out while the vehicle remainsstationary at an inspection zone provided at a downstream end of theautomobile production and assembly line. With this on-line operationchecking method, it is no longer necessary for the automobilemanufacturer to make a huge investment in the construction of AFSinspection facilities including new test course and parking lot. Anotheradvantage attained by the on-line operation checking system is that whena fault is detected during inspection or checking, appropriate measuresto remove the defect can be taken on a real-time basis. This can reducea total number of vehicles produced with faulty AFSs installed therein.

The operation checking process of the present invention is carried outwhile the vehicle remains stationary at the inspection zone.Accordingly, it may occur that the adaptive front lighting system (AFS)does not operate properly when the vehicle is traveling. In thisinstance, however, since operations of the structural components (i.e.,actuators, sensors, and wire harnesses) of the AGS have already bechecked in accordance with the on-line operation checking method of theinvention, one can readily estimate that the operation failure would bedue to a fault in a AFS control program other than the operationchecking program. Thus, the on-line operation checking method of thepresent invention insures high reliability comparable that of theconventional method achieved while the vehicle is traveling on a testcourse.

In the illustrated embodiment, the operation checking program can beexecuted only one time. This is because if the program can be executedmore than one time, it may occur that due to accidental or unintentionalexecution of the operation checking program, the headlamp illuminationis redirected left and right and down and up while the user drives thevehicle. Such accidental activation of the AFS will hinder smooth andsafe driving of the vehicle.

It is possible according to the invention to modify the operationchecking program to be executable more than one time on the conditionthat entry of security code is acknowledged.

INDUSTRIAL APPLICABILITY

With the arrangements so far described, the present invention can beused advantageously as an operation checking method for an adaptivefront lighting system (AFS), which is applicable to on-line inspectionsachieved while the vehicle remains stationary at an inspection zoneprovided at a downstream end of an automobile production and assemblyline.

Although there have been described what are the present exemplaryembodiments of the invention, it will be understood that variations andmodifications may be made thereto within the spirit and scope of theappended claims.

1. A method of checking operation of an adaptive front lighting systemhaving a function of redirecting headlamp illumination in both ahorizontal direction and a vertical direction in accordance withsteering angle, traveling speed and incline of a vehicle, the methodcomprising the steps of: storing an operation checking program inadvance in an electronic control unit installed in the vehicle, theprogram being prepared to activate the adapted front lighting system toperform the function thereof under the control of the electronic controlunit such that the headlamp illumination is redirected leftward,rightward, downward and upward in a predetermined sequence; while thevehicle remains stationary at an inspection zone of an automobileproduction and assembly line, energizing the electronic control unitwith electric power supplied from a battery installed in the vehicle andswitching on headlamps of the vehicle; then, causing the operationchecking program to run, thereby activating the adaptive front lightingsystem; and during a run-time of the operation checking program,performing an inspection to determine whether the headlamp illuminationhas been redirected leftward, rightward, downward and upward in thepredetermined sequence specified in accordance with the operationchecking program.
 2. The method as defined in claim 1, wherein theoperation checking program can be executed only one time.
 3. The methodas defined in claim 1, wherein during the run-time of the operationchecking program, the electronic control unit performs a diagnosticoperation to detect the occurrence of a fault on the basis of answerback signals from structural components of the adaptive front lightingsystem, and when a fault occurs, the electric control unit issues asignal to turn on a warning lamp on a dashboard of the vehicle.
 4. Themethod as defined in claim 1, wherein the inspection performed duringthe run-time of the operation checking program comprises a visualinspection by a human operator.
 5. The method as defined in claim 2,wherein during the run-time of the operation checking program, theelectronic control unit performs a diagnostic operation to detect theoccurrence of a fault on the basis of answer back signals fromstructural components of the adaptive front lighting system, and when afault occurs, the electric control unit issues a signal to turn on awarning lamp on a dashboard of the vehicle.
 6. The method as defined inclaim 2, wherein the inspection performed during the run-time of theoperation checking program comprises a visual inspection by a humanoperator.
 7. The method as defined in claim 3, wherein the inspectionperformed during the run-time of the operation checking programcomprises a visual inspection by a human operator.